Probe drive mechanism and electronic device which uses the same

ABSTRACT

A probe drive mechanism includes a cantilever portion in which a piezoelectric layer is disposed between electrode layers, and a circuit portion which is positioned adjacent to the cantilever portion and drives the cantilever. The cantilever portion and the circuit portion are formed on the same substrate. A protection layer covers the circuit portion and part of the substrate, and the cantilever portion is formed on the protection layer adjacent to the circuit portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of manufacturing an integratedcantilever drive mechanism, a method of manufacturing an integratedprove drive mechanism, a cantilever drive mechanism manufactured by theaforesaid method, a probe drive mechanism manufactured by the aforesaidmethod, a scanning tunnel microscope (STM) which utilizes the aforesaidmechanism and an electronic device such as an information processingapparatus which utilizes the principle so as to record and/or reproduceinformation at high density.

2. Related Background Art

Recently, an STM capable of directly observing the electronic structureof surface atoms of a conductor has been developed (G. Binnig et.al.,Phys. Rev. Lett. 49 (1982) 57) so that an actual space image can bemeasured at a significantly high resolution (nanometer or less)regardless of the fact that the material is single crystal or amorphousstructure.

The STM utilizes a phenomenon that a tunnel current passes when voltageis applied to a portion between a metal probe and a conductive materialand they are brought closer at a distance of about 1 nm and theaforesaid current is changed expotentially because it is very sensitiveto the change in the distance between the two elements.

By scanning the probe while maintaining the tunnel current at a constantlevel, the surface structure in an actual space can be observed at aresolution of an order of an atom. Although the analysis to be performedby using the STM is adapted to only the conductive materials, it hasbeen applied to the analysis of the structure of a thin insulating filmformed on the surface of the conductive material.

Furthermore, the aforesaid apparatus or means employs a method ofdetecting a small electric current so that an advantage is realized inthat the observation can be performed with a small amount of electricitywhile preventing damage to the medium. In addition, wide use of the STMhas been expected because it can be operated in the atmosphere.

In particular, the practical application of the STM to serve as a highdensity recording/reproducing apparatus has been positively promoted asdisclosed in Japanese Patent Laid-Open No. 63-161552 and Japanese PatentLaid-Open No. 63-161553. The aforesaid high density recording and/orreproducing apparatus is so arranged that a probe similar to that of theSTM is used to perform recording while changing the voltage to beapplied to a portion between the probe and a recording medium. As therecording medium, a thin layer made of a π-electron type organiccompound is used, which is a material having a switching characteristicwith a memory capability of voltage-current characteristics. Thereproduction is performed by utilizing the change in the tunnelresistance between the region which has been subject to the aforesaidrecording process and a region which has not been subjected to the same.

As the recording medium adapted to the aforesaid recording method, amedium the surface shape of which is changed due to the voltage appliedto the probe is able to perform the recording/reproducing operations. Ina case where the STM is operated or the recording/reproducing operationby using the STM is performed, the distance from the probe to the sampleor the recording medium must be controlled to an order of Å.Furthermore, the two-dimensional scanning of the probe must becontrolled to an order of several tens of Å in the recording/reproducingoperation for the purpose of recording/reproducing information itemsarranged two-dimensionally on the medium. In addition, in order toimprove the function of the recording/reproducing system, and inparticular, to raise the processing speed, an arrangement has beendisclosed in which a multiplicity of probes are selectively driven todetect the tunnel current.

That is, the relative position between the probe and the medium must bethree-dimensionally controlled at the aforesaid accuracy in a region inwhich a multiplicity of the probes are disposed. The aforesaid controlis performed by using a laminated-type piezoelectric device or acylindrical piezoelectric device, or the like fastened to a portionincluding the probe or a portion including the medium.

However, since the aforesaid devices are not suitable to be integratedalthough a large quantity of change can be allowed, it isdisadvantageous to employ them in a multi-probe type recording and/orreproducing apparatus.

In the aforesaid viewpoint, a method has been disclosed in which theprobe is fastened on a cantilever having a length of hundreds of μm andthe cantilever is driven by a piezoelectric member (C. F. Quate et al.,Transducer, '89, lecture No. D3.6, June 1989. IEEE Electron DeviceLetters 10 (1989), Nov. No. 11).

A method of manufacturing a conventional cantilever will now bedescribed with reference to the drawings.

FIG. 12 illustrates the overall body of a cantilever probe. A substrate1 is made of silicone, and an actuator (drive portion) is formed into acantilever having a piezoelectric bimorph structure. The actuator has azinc oxide layer, a dielectric layer and a metal electrode stackedalternately. FIG. 13 is a cross-sectional view which illustrates thecantilever shown in FIG. 12. The cantilever is arranged in such a mannerthat an upper electrode and a lower electrode are disposed while beingvertically separated from each other and a thin electrode for the tunneltip is disposed at the central portion of the free end portion. Bysuitably combining the way the voltage reaches the portion between theelectrodes, the electrode can be moved in three axial directions.

The aforesaid cantilever is formed as follows:

First, the silicon substrate is subjected to an anisotropic etchingprocess so as to reduce the thickness of the region, which will beformed into the cantilever, to about several tens of μm. An electrode 9is made of metal such as aluminum and a piezoelectric layer 8 made ofzinc oxide or the like is formed by a sputtering method. Eachpiezoelectric layer is held between silicon nitride films by a plasmaCVD (Chemical Vapor Deposition) method.

The upper electrode is covered with gold in order to prevent undesirableoxidation of the surface of a tunnel chip 11. After the overall body ofthe cantilever has been formed, polyimide is applied to the surface to athickness of several μm. A silicon membrane is removed by plasma etchingeffected from the reverse side of the wafer and the polyimide is removedby oxygen plasma, so that the cantilever is formed.

However, since driving of a plurality of the cantilevers, detectionand/or amplification of the tunnel current and feedback of the drivefrom the tunnel current must be selectively performed at the time of therecording/reproducing operation, switching circuits, bias circuits,amplifying circuits and servo circuits and the like must be provided forthe purpose of realizing the aforesaid functions. The aforesaid circuitsmust be formed on the same substrate on which the cantilever is formedin order to reduce the size and to raise the processing speed.

SUMMARY OF THE INVENTION

An object of the present invention is to provide methods ofmanufacturing a novel cantilever drive mechanism and a probe drivemechanism which is capable of maintaining the drive characteristics of acantilever and a cantilever probe and which can be integrally formed.

Another object of the present invention is to provide a cantilever drivemechanism the size of which can be reduced, which can be also used as anactuator, and which exhibits excellent durability.

Another object of the present invention is to provide a probe drivemechanism, the size of which can be reduced, which is suitable to a highdensity recording and reproducing operation and which exhibits excellentdurability.

Another object of the present invention is to provide a scanning typetunnel microscope and an information apparatus enabling size reductionand high speed processing.

The aforesaid objects can be achieved by the following inventions.

According to one aspect of the invention, a method of manufacturing acantilever drive mechanism, having a cantilever portion in which apiezoelectric layer is disposed between electrode layers, and a circuitportion, positioned adjacent to the cantilever portion and driving thecantilever portion, that are formed on the same substrate, comprises thesteps of forming a circuit portion and then forming a cantilever portionafter the circuit portion is formed.

In accordance with another aspect of the present invention, a method ofmanufacturing a probe drive mechanism, having a cantilever portion witha piezoelectric layer disposed between electrode layers, a micro-tip fordetecting a tunnel current and an electrode for receiving the tunnelcurrent, and a processing circuit portion, which is positioned adjacentto the cantilever portion, drives the cantilever portion and detects andamplifies the tunnel current, that are formed on the same substrates,comprises the steps of forming the processing circuit portion, and thenforming the cantilever portion after the processing circuit portion isformed.

In accordance with still another aspect of the present invention, amethod of manufacturing a cantilever drive mechanism, having acantilever portion with a piezoelectric layer disposed between electrodelayers, and a circuit portion, positioned adjacent to the cantileverportion and which drives the cantilever portion, that are formed on thesame substrate, comprises the steps of forming a first insulating layeron the substrate, forming a second insulating layer on the firstinsulating layer, patterning and etching the second insulating layer toremove a portion where the cantilever portion will be formed, forming anelectrode layer on the first and second insulating layers, patterningand etching the electrode layer to remove a portion where the cantileverportion will be formed, removing the first insulating layer at a portionwhere the cantilever portion will be formed, forming a protection layeron the electrode layer in the first and second insulating layers to formthe circuit portion, stacking an electrode layer and a piezoelectriclayer on the protection layer adjacent to the circuit portion, andremoving the substrate and a protection layer from the cantileverportion.

In accordance with yet another aspect of the present invention, a methodof manufacturing a probe drive mechanism having a cantilever portion,with a piezoelectric layer disposed between electrode layers, amicro-tip for detecting the tunnel current and an electrode forreceiving the tunnel current, and a processing circuit portion,positioned adjacent to the cantilever portion and which drives thecantilever portion and detects and amplifies the tunnel current, thatare formed on the same substrate, comprises the same steps as set forthabove with respect to the method of manufacturing the cantilever drivemechanism.

In accordance with another aspect of the present invention, a method ofmanufacturing a cantilever drive mechanism, having a cantilever portionwith a piezoelectric layer disposed between electrode layers, and acircuit portion, positioned adjacent to the cantilever portion and whichdrives the cantilever portion, that are formed on the same substrate,comprises the steps of forming a first insulating layer on thesubstrate, forming a second insulating layer on the first insulatinglayer, forming an electrode layer on the second insulating layer,patterning and etching the electrode layer to remove it from a portionwhere the cantilever portion will be formed, removing the firstinsulating layer and the second insulating layer at a portion where thecantilever portion will be formed, stacking a protection layer on theelectrode layer and the first and second insulting layers to form acircuit portion, stacking an electrode layer and a piezoelectric layeron the protection layer adjacent to the circuit portion, and removing aportion of the substrate and a protection layer to form the cantileverportion.

In accordance with yet another aspect of the present invention, a methodof manufacturing a probe drive mechanism, having a cantilever portionwith a piezoelectric layer disposed between electrode layers, amicro-tip for detecting a tunnel current and an electrode for receivingthe tunnel current, and a processing circuit portion, positionedadjacent to the cantilever portion and which drives the cantilever anddetects and amplifies the tunnel current, that are formed on the samesubstrate, comprises the same steps as discussed above for manufacturingthe cantilever drive mechanism.

In accordance with still another aspect of the present invention, acantilever drive mechanism comprises a cantilever portion having apiezoelectric layer disposed between electrode layers. and a circuitportion positioned adjacent to the cantilever portion and which drivesthe cantilever portion. The cantilever portion and the circuit portionare formed on a single substrate, with the circuit portion being coveredwith a protection layer and the cantilever portion being formed on aprotection layer adjacent to the circuit portion.

In accordance with another aspect of the present invention, a probedrive mechanism comprises a cantilever portion having a piezoelectriclayer disposed between electrode layers, a micro-tip for detecting atunnel current and an electrode for receiving a tunnel current, aprocessing circuit portion, positioned adjacent to the cantileverportion, which drives the cantilever and detects and amplifies thetunnel current, and a substrate for supporting the cantilever portionand the processing portion. The circuit portion is covered with aprotection layer and a cantilever portion is formed on the protectionlayer adjacent to the processing circuit portion.

In accordance with yet another aspect of the present invention, acantilever drive mechanism comprises a cantilever portion having apiezoelectric layer disposed between electrode layers, a circuit portionpositioned adjacent to the cantilever portion and which drives thecantilever portion, and a substrate for supporting the cantileverportion and a circuit portion. A circuit portion is covered with aprotection layer, and the cantilever portion is formed on the protectionlayer adjacent to the circuit portion, wherein the piezoelectric layerof the cantilever portion is composed of a plurality of stacked layershaving polarization axes in different polarization directions.

In accordance with still another aspect of the present invention, aprobe drive mechanism comprises a cantilever portion having apiezoelectric layer disposed between electrode layers, a micro-tip fordetecting a tunnel current and an electrode for receiving the tunnelcurrent, a processing circuit portion positioned adjacent to thecantilever portion which drives the cantilever and detects and amplifiesthe tunnel current, and a substrate for supporting the cantileverportion and the circuit portion. The circuit portion is covered with aprotection layer and the cantilever portion is formed on the protectionlayer adjacent to the circuit portion, wherein the piezoelectric layerof the cantilever portion is composed of a plurality of stacked layershaving polarization axes in different polarization directions.

According to another aspect of the present invention, there is providedprobe drive mechanism comprising a plurality of probe drive mechanisms,wherein the probe drive mechanisms are formed on the same substrate.

According to another aspect of the present invention, there is provideda scanning tunnel microscope comprising a probe drive mechanism, meansfor relatively moving the probe drive mechanism with respect to a samplesurface to be observed, means for applying voltage between the probe andthe sample, and means for detecting an electric current which passesbetween the probe and the sample.

According to another aspect of the present invention, there is providedan information apparatus comprising a probe drive mechanism, means forrelatively moving the probe drive mechanism with respect to a recordingmedium, means for applying voltage for recording and/or reproducinginformation between the probe and a sample, and means for detecting anelectric current which passes between the probe and the sample.

Other and further objects, features and advantages of the invention willbe appear more fully from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view which illustrates a probe drivemechanism according to the present invention;

FIGS. 2 (a) to 2 (k) are cross-sectional views which illustrate a firstaspect of the manufacturing process of the manufacturing methodaccording to the present invention;

FIGS. 3 (a) to 3 (d) are a cross-sectional views which illustrate asecond aspect of the manufacturing process of the manufacturing methodaccording to the present invention;

FIG. 4 illustrates a multi-probe head integrally formed on the siliconsubstrate by the manufacturing method according to the presentinvention;

FIG. 5 is a block diagram which illustrates an information processingapparatus which uses the multi-probe head obtained by the manufacturingmethod according to the present invention;

FIG. 6 is a detailed block diagram which illustrates the probe headcontrol circuit shown in FIG. 4;

FIGS. 7 (a) to 7 (f) are cross-sectional views which illustrate amanufacturing method to be subjected to a comparison with the presentinvention;

FIG. 8 illustrates hillock generated by the manufacturing method shownin FIG. 7;

FIGS. 9 (a) to 9 (e) are cross-sectional views which illustrate theprocess of manufacturing a cantilever portion according to the presentinvention;

FIG. 10 is a structural view which illustrates an ion beam evaporatingdevice for use to manufacture the cantilever portion according to thepresent invention;

FIG. 11 is a block diagram which illustrates a scan type tunnelmicroscope to which the probe mechanism according to the presentinvention is applied;

FIG. 12 is a perspective view which illustrates a conventionalcantilever probe; and

FIG. 13 is a cross-sectional view which illustrates a cantilever portionshown in FIG. 12.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the knowledge obtained by the inventor of the presentinvention, it was found that a process of manufacturing a switchingcircuit and the like and a process of manufacturing a cantilever portionmust be independently performed from each other because the material orthe like is different from each other when the switching circuit and thelike and the cantilever are manufactured on the same substrate.Furthermore, it was found that a very efficient effect can be obtainedwhen the cantilever portion is formed after the processing circuitportion has been formed. Since the cantilever region does not requirethe wiring and interlayer insulating layer used at the process offorming the switching circuit and the like, they must be removed beforethe process of forming the cantilever is performed.

In order to be subjected to a comparison with the present invention, amethod of forming the processing circuit and the cantilever on the samesubstrate will now be described with reference to the drawings.

FIG. 7 (a) illustrates a state where a process of photolithography andetching an interlayer insulating layer 3 of a circuit device has beencompleted by a conventional method, in which the diffusion process hasbeen completed. The insulating layer 3 in the cantilever region must beremoved at the time of etching in order to establish a contact betweenthe substrate 1 and an electric line 6 to be described later. Then, theelectrode layer 6 is formed by using a sputter device or the like, sothat a structure shown in FIG. 7 (b) is realized. Then, the electrodelayer 6 is subjected to a photolithographic and etching process, so thatthe wiring process of the circuit device is completed (see FIG. 7 (c)).When an Si₃ N₄ or an SiO₂ layer 7 serving as a mask layer at the time ofthe process of anisotropic-etching the silicon substrate 1 is formed, astate shown in FIG. 7 (d) is realized. When an electrode layer 9 and apiezoelectric member layer 8 are then stacked on the cantilever portionadjacent to the circuit portion, a cantilever layer is formed. Then, amicro-tip 11 is formed (see FIG. 7 (e)). An electrode layer 10 forestablishing a connection between the electrode 9 for driving thecantilever or taking the tunnel current and the wiring electrode 6 inthe circuit portion is formed, and then the Si-substrate 1 and the masklayer 7 in the lower portion of the cantilever are removed. Hence, a(multi-) probe drive mechanism so arranged that the cantilever having amicro-tip at the front portion thereof and the processing circuit areformed on the same substrate 1 is formed as shown in FIG. 7 (f). FIG. 7(f) illustrates a state where an nMOS drain 12 of the processing circuitand the electrode 9 for driving the cantilever are connected to eachother.

However, the aforesaid method in which the unnecessary interlayerinsulating layer and the electrode positioned in the cantilever regionare sequentially removed encounters a fact that the electrode made of Alor an Al-Si alloy for used as the material for the electrode ispositioned in direct contact with Si, which is the substrate. It leadsto a fact that Al, which is the material of the electrode, and Si arepartially eutectic-reacted with each other after the electrode layer hasbeen formed. Therefore, high density hillock 15 having a size of severalmm and a height of thousands of Å as shown in FIG. 8 is left after theelectrode material has been removed (corresponding to a state shown inFIG. 7 (c)). Therefore, problems arise in that the piezoelectric layergrows excessively, the driving electrodes are undesirably electricallyconnected to each other or the wires are disconnected after thecantilever has been formed.

The present invention is so arranged that the direct contact between theSi of the substrate and the electrode material, which will cause thehillock, is prevented, so that a manufacturing method capable ofovercoming the aforesaid problems is provided.

Then, the present invention will now be described in detail withreference to examples. However, the present invention is not limited tothe following examples.

EXAMPLE 1

FIG. 1 is a cross-sectional view ,which illustrates a probe drivemechanism which is obtained by the manufacturing method according to thepresent invention and in which the cantilever and the processing circuitare formed on the same substrate.

The manufacturing process is composed of the process of forming theprocessing circuit portion, an ensuing process of forming the cantileverportion, a process of forming a micro-tip, and a process of removing thesubstrate. Then, the aforesaid processes will now be sequentiallydescribed.

As the device for the circuit portion, a CMOS transistor is used.However, only the NMOS portion is illustrated here for the purpose ofsimplifying the description. As the substrate 1, an n⁻ type (100)silicon having a resistivity of 1 to 2 Ωcm is used, and a thermallyoxidized film layer 21 having a thickness of 7000Å is formed to serve asan implant mask layer by using an oxidizing furnace. Then, a P wellregion 22 is removed, a thermally oxidized film having a thickness of1000Å is formed to serve as a buffer layer by an oxidizing furnace. Anion implant device is used to implant B (boron) ions and a heattreatment at 1150° C. is performed for 85 minutes by using a diffusionfurnace so that the P well region 22 is formed (see FIG. 2 (a)). Then,the thermally oxidized film layer 21 is removed from the entire surfaceand a thermally oxidized film is newly formed to a thickness of 500Å,and then an LPCVD (low pressure CVD) device is used to form a 2000Åsilicon nitride film. Then, the silicon nitride film in the portionsexcept for the region in which the NMOS, PMOS cantilever will be formedis removed. Then, a resist process is performed, and then P (phosphorus)ions are implanted for stopping the P channel. Similarly, B (boron) ionsare implanted for the purpose of stopping the N channel after the resistprocess has been completed. By using an oxidizing furnace, a thermallyoxidized film serving as the first insulating film is formed to athickness of 8000Å, so that a LOCOS (Local Oxidation of Silicon) layer 2is formed. Then, the silicon nitride film and the oxidized films exceptfor the LOCOS layer 2 are removed, so that a state shown in FIG. 2 (b)is realized. Then, the oxidizing furnace is used to form a thermallyoxidized film to a thickness of 350Å, a gate film layer 23 is formed,and BF₂ ions are implanted to the overall surface for the purpose ofcontrolling Vth of the MOS. By using the LPCVD device, a poly-siliconfilm is formed to have a thickness of 4500Å and by using the implantdevice the phosphorus ions are implanted to the entire surface. Then,the poly-silicon on the reverse side is removed and annealing isperformed at 950° C. for 30 minutes in the diffusion furnace before thepoly-silicon film is patterned and etched. Then, the poly-silicon filmis oxidized to form a gate electrode 4, so that a state shown in FIG. 2(c) is realized.

Then, the resist is patterned and arsenic ions are implanted so that thesource and drain 12 of the NMOS transistor are formed. Similarly, theresist is patterned and BF₂ ions are implanted so that the source andthe drain of a PMOS transistor are formed. Then, annealing is performedat 1000° C. for 5 minutes in the diffusion furnace, and a BPSG (boron,phosphorus dope silicon oxidized film) film is formed to a thickness of7000Å so that an interlayer insulating layer 3 serving as a secondinsulating layer is formed. Then, annealing at 950° C. for 20 minutes isperformed, so that a state shown in FIG. 2 (d) is realized.

In order to establish a contact between the transistor in the circuitportion and the electric line, patterning is performed so as to removethe BPSG layer 3 and the gate layer 23 and to form a contact hole 19(see FIG. 2 (e)). By using a sputtering device, an aluminum-silicon filmis formed (see FIG. 2 (f)), and patterning and etching are performed sothat the wiring layer (electrode layer) 6 is formed (see FIG. 2 (g)).Then, the BPSG layer 3 and the gate film layer 23 in the cantileverregion are removed so that a state shown in FIG. 2 (h) is realized.Furthermore, a plasma CVD device is used to form SiON films torespectively have thicknesses of 3000Å, 5000Å, 7000Å and 12000Å beforethey are patterned. As a result, a protection layer 7 is formed (seeFIG. 2 (i)) . Incidentally, Si₃ N₄ or SiO₂ may be used as the materialfor the protection layer. The reason why several types having protectionlayers of different thicknesses are formed lies in that the cross talktaking place due to the parasitic capacity between the electrodes of thecantilever and the passivation characteristics of the protection layerof the circuit portion depending upon the thickness of the protectionlayer must be evaluated.

Then, the layers to be stacked to form the cantilever will now bedescribed. As the lower electrode layer 9, a chrome film is formed tohave a thickness of 20Å by using an evaporating device and a gold filmhaving a thickness of 1000Å is formed by a lift off method. Then, thesputter device is used to form a zinc oxide layer to have a thickness of5000Å to serve as a piezoelectric member layer 8, and then a gold layeris formed to a thickness of 2000Å and a zinc oxide layer is formed to athickness of 3000Å by the lift off method. Then, a gold layer is formedto a thickness of 1000Å so that the cantilever portion is formed bystacking and a bimorph structure composed of the electrode layer 9 andthe piezoelectric member layer 8 is formed (see FIG. 2 (j)).

Then, the electrode of the cantilever portion and the electrode of thecircuit portions are connected to each other by partially removing thepiezoelectric member layer 8 and the protection layer 7 by etching.Furthermore, a contact hole is formed and an aluminum film is formed bythe lift off method so that a connecting electrode layer 10 is formed.Then, a micro-tip 11 is formed to a height of 7 μm by a method in whichthe resist opening portion is used. Incidentally, the necessity offorming the aforesaid micro-tip can be eliminated in the process ofmanufacturing the cantilever drive mechanism.

As the material of the micro-tip 11, it is preferable that noble metalsuch as Au, Pt, and Pd be used. Furthermore, it is preferable that thematerial of the piezoelectric member layer be material such as AlN, ZnO,Ta₂ O₃, PbTiO₃, Bi₄ Ti₃ O₁₂, BaTiO₃ and LiNbO₃ having a piezoelectriccharacteristic.

Finally, the silicon substrate 1 below the cantilever is removed byanisotropic etching and then the protection layer is removed by theplasma device (see FIG. 2 (k)), so that a probe drive mechanism as shownin FIG. 1 and arranged so that the cantilever and the processing circuitare formed on the same substrate.

Since the cantilever and the processing circuit can be integrally formedaccording to this embodiment, the size of the multi-probe drivemechanism can be reduced. Furthermore, in the case where the thicknessof the protection layer is made to be 3000Å and preferably 5000Å, thecross talk between the electrodes of the cantilever and the channel canbe prevented and also the passivation characteristics can be improved.In addition, since the structure is so arranged that the electrode layer6 of the circuit portion is not positioned in contact with the siliconsubstrate, the generation of the hillock in the cantilever region due tothe alloy forming of aluminum and silicon can be prevented. Therefore,electrical short circuits, disconnections and excessive growth of thepiezoelectric member can be prevented, therefore causing a satisfactoryeffect to be obtained.

EXAMPLE 2

This example is so arranged that a LOCOS layer is formed in place of thegate film layer and the BPSG layer in the lower layer of the electrodelayer in the circuit portion in the cantilever region according toExample 1.

FIG. 3 (a) illustrates an NMOS transistor in the circuit portion and thecantilever region in a state where the electrode layer in the circuitportion has not been formed. This example is so arranged that thecantilever region is covered with the LOCOS layer. After the electrodelayer 6 has been formed (see FIG. 3 (b)), the LOCOS layer in theportion, in which the cantilever is formed, is removed (see FIG. 3 (c)).The ensuing processes are performed similarly to Example 1, so that aprobe drive mechanism according to the present invention and as shown inFIG. 3 (d) is obtained.

Also the probe mechanism according to this example enables asatisfactory effect to be obtained similarly to Example 1.

EXAMPLE 3

With reference to this example, the description will be made about aninformation processing apparatus which uses the multi-probe drivemechanism obtained by the manufacturing method according to the presentinvention. Referring to FIG. 4, the aforesaid multi-heads 31 and theperipheral circuit are formed on the same substrate, the substrate beinga silicon substrate 30. The information processing apparatus furthercomprises an X-shift register 35, a Y-shift register 36, a circuitportion 37 including an electrostatic capacity, a switching device andan amplifier, a micro-tip 11, a cantilever 32 and a matrix circuit 33and the like.

Reference numeral 34 represents a bonding pad for connecting a signalline, the bonding pad being disposed on one side of the multi-probeheads 31 and on each of the two opposite sides. Hence, the recordingmedium can be moved in a direction running parallel to the bonding padto perform the recording and/or reproducing operation.

Although the example shown in FIG. 3 is arranged so that the drivedevice is integrally formed by using the silicon substrate, the presentinvention is not limited to the silicon substrate. A wafer formed due tothe epitaxial-growth of a silicon thin film on a sapphire substrate maybe used. Furthermore, semiconductor layers and substrates such as apolysilicon thin film allowed to grow on a quartz substrate and a solidphase epitaxial film may be used regardless of the form thereof.

FIG. 5 is a block diagram which illustrates the information processingapparatus having the probe drive mechanism obtained by the manufacturingmethod according to the present invention. Each of the elements shown inblock outline in FIG. 5, as well as in FIGS. 6 and 11, is well known perse, and a specific type of construction is not critical to carrying outthe invention or to a disclosure of the best mode for carrying out theinvention. Reference numeral 31 represents a multi-probe head, 41represents an actuator for scanning the multi-probe head in the XYplane, and 42 represents a scanning circuit. Reference numeral 43represents a recording medium, 44 represents an actuator for correctingthe inclination of the recording medium so as to cause the micro-tips ofthe multi-probe head to be disposed equally, and 45 represents aninclination correction control circuit. Reference numeral 46 representsa structural member for supporting the aforesaid elements.

A recording medium preferably used in the present invention comprises arecording layer on an electrode, which exhibits electrical memoryeffect, as disclosed in Japanese Patent Laid-Open Application No.63-161552 or No. 63-161553.

As the above-mentioned recording layer, it becomes possible to use amaterial having the memory switching phenomenon (electrical memoryeffect) in the current-voltage characteristics, for example, an organicmonomolecular film or its built-up film (LB film) having moleculeshaving the group having only the conjugated π electron level and thegroup having only the σ electron level in combination laminated on theelectrode. The electrical memory effect enables transition (switching)reversible to the low resistance state (ON state) and the highresistance state (OFF state) by applying a voltage exceeding thethreshold value capable of transition of the above-mentioned organicmonomolecular film or its built-up film, etc. to the states exhibiting 2or more different electroconductivities under the state arranged betweena pair of electrodes (ON state, OFF state). Also, the respective statescan be retained (memorized) even when application of the voltage may bestopped.

The control of the multi-probe head 31 is performed by a probe headcontrol circuit 47. Data to be written is encoded by an encoder 48before it is transferred to a probe head control circuit 47. As aresult, the multi-probe head 31 is driven so that data is written to therecording medium. When data is read, an address to be read is generatedby a processor (omitted from illustration) and the probe head controlcircuit 47 is driven. The probe head control circuit 47 reads a signalof each probe from the multi-probe head 31 in accordance with theaforesaid address so as to transfer the signal to the decoder 48. Thedecoder 48 performs an error detection or error correction from theaforesaid signal before it transmits data.

The control of the distance between probe mediums and that of theinclination of the multi-probe head are performed similarly to thedescription made above. The probe head control circuit 47 directly readsinformation about the tunnel current which passes through each probecurrent. A circuit 49 for controlling the distance between the probe andthe medium detects the deviation from the reference position. TheZ-directional control of each micro-tip is controlled by a cantileverdrive circuit 50. In a case where the attitude of the multi-probe headmust be corrected, the inclination control circuit 45 is used.

FIG. 6 is a detailed block diagram which illustrates the probe headcontrol circuit 47 for writing and/or reading data.

The timing for accessing each probe electrode is controlled on the basisof a scanning clock 51. The aforesaid scanning clock is made to be clocksignal CLK-Y for the multi-probe head, the clock signal CLK-Y beingsupplied to a Y-address counter 52. The Y-address counter 52 has thesame number of counts as that of the steps of a Y-shift register of themulti-probe head. The carry output from the Y-address counter 52 is madeto be clock signal CLK-X of the multi-probe head, the clock signal CLK-Xbeing supplied to an X-address counter 53. The X-address counter 53 hasthe same number of counts as that of the steps of the X-shift registerof the multi-probe head. The count output from the X and Y addresscounters is made to be a probe address 54.

Read output Vout from the multi-probe head is supplied to a comparator55. The comparator 55 binary-coding read output Vout while making Vref56 as the reference voltage. The binary output is written to a recordingunit of a probe control table 57 instructed with the probe address 54.

Each of probe control tables 57 to 59 has one to several pages each ofwhich is composed of a temporary storage memory constituted by recordingunits of the same number as the number of the probes of the multi-probehead. Each recording unit records at least 6 logical values consistingof record data logical value read from the multi-probe head and drivestatus values for instructing reading, writing on, writing off anddeletion operations.

As for the access of the multi-probe head, φr (read signal), φd(deletion signal), φw (write signal) signals are generated so as tocontrol the probe electrode in accordance with the drive status value ofeach unit of the probe control table.

When data is read by the multi-probe head, the micro-tip is scanned to apredetermined position of the recording medium. Then, a host control CPU(omitted from illustration) is used to register the drive state value toa recording unit which corresponds to the address of the probe whichreads data of the probe control tables 57 to 59 via a data bus and anaddress bus. After the sequence reading operations with the multi-probehead have been completed, the read data logical value of the recordingunit of the previously instructed probe address is read, and the errordetection or the error correction is performed by the encoder 48. Thus,the reading operation is completed.

When data is written, supplied data is encoded by the encoder 48 beforethe logical values of the encoding language are, as the drive statusvalue, registered to the probe control tables 57 to 59. In accordancewith the registered logical data, writing signals are sequentiallytransferred to the multi-probe head.

Each of the recording units does not continuously register the writingor the deletion operations with respect to an access cycle for eachpage. That is, each micro-tip does not continuously permit the writingoperations but the writing and deletion are performed while performingthe reading operation without exception. The aforesaid arrangement isrequired to control the distance between the probe electrode and therecording medium in accordance with the amplitude of the signal at thetime of the reading operation.

Furthermore, writing or deletion registration is not performed withrespect to all of the recording units in one page. That is, all of thematrix-disposed probe electrodes of the multi-probe head do notsimultaneously perform the writing operation. The aforesaid arrangementis required to control the inclination to always hold the multi-probehead to run parallel to the recording medium.

The Z-directional control of the micro-tip and the control of theinclination of the probe head are performed by the circuit 49 forcontrolling the distance between the probe and the medium by using thesignal attribute generated from tunnel current equivalent signal Jtgenerated from the signal Vout and signals φr, φd and φw and a probe Zcontrol signal group 61 constituted by the probe address. That is, thecircuit 49 for controlling the distance between the probe and the mediummakes a reference to the probe control table and drives a cantileverdrive circuit 50 and the inclination correction circuit 45 in accordancewith the output signal Vout from the probe which is in the readingstate.

Incidentally, the cantilever for use in the structure according to thisembodiment is arranged to have an electrostatic or a piezoelectricactuator in addition to the probe electrode so that the distance betweenthe probe electrode and the recording medium can be controlledrespectively. The aforesaid actuators are driven in response to a signalsupplied from the cantilever drive circuit 50 via a circuit (omittedfrom illustration) provided for the multi-probe head.

By using the write/read control method in which the aforesaid probecontrol table is used, the location of the probe electrodes to bebrought to the reading state can be arbitrarily determined in such amanner that the all of the probe electrodes have an equal writing andreading ratio. As a result of the aforesaid control, the Z-directionalcontrol of the probe can be stably performed at high speed regardless ofwriting and deletion data.

As described above, the manufacturing method according to the presentinvention enables a probe mechanism to be obtained in which integrationcan be realized efficiently while maintaining the drive characteristicsof the cantilever and the tunnel current detection characteristics andas well as reducing the parasitic capacity generated between theelectrodes of the cantilever.

Furthermore, an STM and an information processing apparatus can beprovided which is capable of stably recording and/or reproducinginformation at high speed while reducing the size thereof.

Although the aforesaid example employs the cantilever having a bimorphstructure provided with an intermediate electrode, a further preferableexample in which a cantilever having no intermediate electrode will nowbe described.

A cantilever of the aforesaid type is a thin film cantilever which canbe formed into a multi-cantilever and integrated, which has a largequantity of displacement equivalent to that of the conventionalcantilever comprising the piezoelectric bimorph structure having anintermediate electrode, which is capable of easily controlling thestress of each of the stacked layers, which is capable of preventinggenerations of cracks in the film and separation of the film, and whichcan be manufactured by a simple manufacturing process.

For example, the description will be made with reference to FIG. 9 (c).In a case where an electric field is applied to a portion between alower electrode 9-1 and an upper electrode 9-2, a phenomenon takes placein that either of a first piezoelectric thin film layer 8-1 or a secondpiezoelectric thin film layer 8-2 is displaced in the extendingdirection and the residual layer is displaced in the contractiondirection though the same electric field is applied because thepolarization direction of the first piezoelectric thin film layer 8-1 isdifferent from that of the second piezoelectric thin film layer 8-2.Therefore, the free end of a cantilever type displacement device can bedisplaced upwards or downwards a considerable amount. Furthermore, anintermediate layer 8-3 formed continuously from the layers 8-1 and 8-2and having a different polarization direction from that of the layer 8-2is present in the interfacial surface between the piezoelectric thinfilm layer 8-1 and 8-2, and the adhesion between the layers 8-1 and 8-2can be improved. As a result of the aforesaid structure, theintermediate electrode can be omitted from the structure, causing aportion in the interface between the electrode and the piezoelectricmember in which the stress will be generated to be reduced. Furthermore,the generation of the stress in the interface between two piezoelectricthin films having different polarization directions can be substantiallyprevented because the same material is used and therefore the two layershave the same crystal lattice and substantially the same thermalexpansion coefficient. As described above, the internal stress presenton the interface can be minimized. In addition, since the adhesive layeris not present between the piezoelectric members, satisfactorydurability against repeated displacement can be realized.

That is, the cantilever-like displacement device according to thepresent invention enables the intermediate electrode to be omitted fromthe conventional cantilever comprising the piezoelectric bimorph.Therefore, the stress control between the piezoelectric thin films canbe easily performed and a problem of the separation of the film in theinterface can be overcome. Furthermore, the generation of the cracks inthe piezoelectric film can be prevented. As a result, a thin filmcantilever type displacement device which can be formed into amulti-cantilever structure, which can be integrated, and which exhibitssatisfactory durability against repeated displacement and acantilever-type probe which uses the aforesaid cantilever can be stablyprovided by a simple manufacturing process.

In order to describe the present invention in detail, the process of thestudy to establish the present invention will now be described.

Experiment: Stacking Layers Having Different Polarization Directions andForming of Piezoelectric Displacement Device

Description will now be made about an experimental example in whichpiezoelectric thin films composed of two layers having differentpolarization directions are continuously stacked and the stackedpiezoelectric thin film is used to manufacture the thin film cantilevertype displacement device according to the present invention.

The process of forming the circuit portion (see FIG. 1 (i)) wasperformed similarly to Example 1. Then, as shown in FIG. 9 (a), thelower electrode 9-1 was formed on the protection layer 7. The substrate1 was made of Si, the protection layer 7 was made of SiON, and the lowerelectrode 9-1 was formed by a Cr/Au stacked film by an ordinaryresistance hot evaporation process.

As shown in FIG. 9 (b), the piezoelectric thin film 8 was formed bycontinuously stacking and depositing the first piezoelectric thin filmlayer 8-1, the intermediate layer 8-3 and the second piezoelectric thinfilm layer 8-2. At this time, an ion beam evaporation device shown inFIG. 10 was used in such a manner that the raw material of the thin filmwas injected into an evaporation source 69 and it was evaporated byheat. Furthermore, the film was formed in such a manner that theionizing current and the accelerating voltage were made differentbetween the first piezoelectric thin film layer 8-1 and the secondpiezoelectric thin film layer 8-2 while spraying a reactive gasintroduced through a gas injection port 65 to the surface of thesubstrate.

First, the first layer 8-1 was deposited while making the ionizingcurrent and the accelerating voltage to be suitable levels under theaforesaid film forming conditions. Then, the ionizing current wasinstantaneously increased while continuing the evaporation, and the filmforming operation was continued while reversing the polarity of theaccelerating voltage, so that the second layer 8-2 was deposited whileintervening the intermediate layer 8-3.

Then, the upper electrode 9-2 was formed by evaporating Au by theordinary resistance hot evaporation process as shown in FIG. 9 (c).

After the lower electrode 9-1, the piezoelectric thin film 8 and theupper electrode 9-2 had been stacked as described above, thedisplacement device was manufactured by performing patterning into thecantilever shape as shown in FIG. 9 (d). The patterning process wasperformed by using the photoresist, dry etching was performed by using areactive ion etching device, and the resist was separated. Then, thesubstrate was subjected to the anisotropic etching process by using apotassium hydroxide solution so that an end portion of the device wasremoved together with the protection layer 7 and the substrate in thelower portion of the device was also removed. Thus, the device wasmanufactured.

When a positive electric field was applied to the upper electrode 9-2after the lower electrode 9-1 of the thus manufactured cantilever typedisplacement device was grounded, the free end of the device wasupwardly displaced. When a negative electric field of the same intensitywas applied to the same, the free end was displaced downwardly by thesame degree.

As described above, the cantilever type displacement device according tothe present invention is manufactured as shown in FIG. 9 in such amanner that the lower electrode 9-1, a piezoelectric thin film 8composed of a plurality of layers having different polarizationdirections, that is, the first layer 8-1, the intermediate layer 8-3 andthe second layer 8-2, and the upper electrode 9-2 are deposited on thesubstrate 1 while intervening the protection layer 7 before patterningis performed, and the substrate in the lower portion of the device isremoved except for the one end portion of the device. The process ofpatterning the device portion is performed by combining thephotolithography by using an ordinary photoresist, dry etching such asthe reactive ion etching, and wet etching by using oxide or alkalietching liquid.

If a suitable etching method cannot be adapted to the electrode, thelift off process is employed. The removal of the substrate in the lowerportion of the device is performed by anisotropy etching of thesubstrate. In an ordinary case where Si is used, a typical method inwhich an Si₃ N₄ layer is used to serve as a mask layer which is thenpatterned, and potassium hydroxide solution is used can be employed.

The cantilever type probe which uses the aforesaid displacement devicecan be manufactured as shown in FIG. 9 (e) in such a manner that themicro-tip 11 for input and/or output information is provided at the freeend of the device and the circuit portion and the electrode of thecantilever portion are brought into contact with each other. Theinformation processing apparatus which uses the aforesaid cantilevertype probe utilizes the principle of the STM and performs recording andreproducing by means of the tunnel current which passes between theprobe and the recording medium. The block diagram of a typical apparatusis shown in FIG. 11. In accordance with the same principle and the samemethod, the surface observation can be performed by the STM.

The thin film material for use to form the piezoelectric thin film 8 isnot limited particularly if the material has the piezoelectriccharacteristics and performs the spontaneous polarization, the materialbeing exemplified by AlN, ZnO, Ta₂ O₃, PbTiO₃, Bi₄ Ti₃ O₁₂, BaTiO₃,LiNbO₃ and the like.

The method manufacturing the piezoelectric thin film 8 is not limitedparticularly. For example, the evaporation method including theaforesaid ion beam evaporation method, the sputtering method, the CVDmethod, or the sol and gel method may be employed. Furthermore, anassist means such as plasma, active gas and/or light irradiation may becombined in addition to the aforesaid film forming method.

Although the method of controlling the polarization direction of thethin film at the time of depositing the piezoelectric thin film dependsupon the method of forming the thin film, the following means areschematically exemplified to correspond to the employed method.

(1) Evaporation Method (Ion Beam Evaporation Method Included)

Control of the ionizing current and accelerating voltage (the ionizingcurrent is made to be a suitable value selected from a range from 0 to500 mA, and the accelerating voltage is made to be a suitable levelselected from a range from -10 kV to +10 kV)

Exchange of evaporation material (metal ←→ compound)

(2) Sputter Method

Exchange of target material (metal ←→ compound)

(3) CVD Method

Type of the raw material gas, and the like

Methods of controlling the polarization direction of the thin filmcommonly employed to a multiplicity of thin film manufacturing methodsare exemplified as follows:

change of the temperature of the substrate

doping of different element to the piezoelectric thin film

control of the assist condition (plasma, active gas, light irradiation)

application of a bias electric field to the substrate

control of the state of the base of each layer

The aforesaid control methods may be employed while being combined in aplace of sole employment. Furthermore, it may be used between the layersor temporarily used after the film has been formed as well ascontinuously used in the entire process of depositing the piezoelectricthin film. That is, for example as shown in FIG. 9 (b), the first layer8-1 is deposited and then the crystal state of a predetermined thicknessof the first layer 8-1 is temporarily changed by plasma irradiation, andthen the second layer 8-2 is deposited under the same conditions asthose for forming the first layer 8-1, so that the following structurecan be, for example, realized that the polarization direction of theinitial stage of the forming process is made to be opposite to that ofthe first layer 8-1 and the polarization direction of the overall bodyof the second layer 8-2 is made to be opposite to that of the firstlayer 8-1.

As the material used to form the lower electrode 9-1 and the upperelectrode 9-2, it is preferable that noble metals such as Au, Pt and Pdbe used. Al or the like may be used as the electrode material in a casewhere AlN or ZnO is used as the material for forming the piezoelectricthin film 8, and can be formed when the temperature of the substrate isat a relatively low level, is used. Furthermore, a conductive oxide suchas ITO may be used. In any case, a proper contact layer may be used inorder to improve the adhesion with the piezoelectric thin film 8. It isexemplified by Cr layer in the Cr/Au stacked film for used in the lowerelectrode 9-1 in the aforesaid experiment.

Then, the present invention will now be described in detail withreference to examples.

EXAMPLE 4

FIGS. 9 (a) to 9 (e) schematically illustrate the method ofmanufacturing the cantilever-like displacement device according to thisexample and a cantilever type probe which uses it.

Referring to FIGS. 9 (a) to 9 (e), reference numeral 1 represents asubstrate, 7 represents a protection layer, 9-1 represents a lowerelectrode, 8 represents a formed piezoelectric thin film composed of aplurality of layers having different polarization directions, that is, afirst piezoelectric thin film layer 8-1, an intermediate layer 8-3 and asecond piezoelectric thin film layer 8-2. Reference numeral 9-2represents an upper electrode and 11 represents a micro-tip forinputting and/or outputting information.

FIG. 10 is a schematic view which illustrates an example of an ion beamevaporating device for use to stack the piezoelectric thin film 8 of thedevice according to this example. Referring to FIG. 10, referencenumeral 1 represents a substrate, 68 represents a vacuum chamber, 69represents an evaporation source having a crucible and a heating device,60 represents a substrate holder, 61 represents an electron emittingsource, 62 represents an accelerating electrode, and 63 represents apower source for the acceleration. Although the illustration is so madethat the substrate side is made to be negative, the polarity may bereversed. Reference numeral 64 represents a jetted steam ion beam, and65 represents a gas jetting port.

Incidentally, the vacuum chamber 68 can be exhausted by a device(omitted from illustration). Furthermore, the temperature of thesubstrate 1, the temperature of the evaporating source 69, the ionizingcurrent to be supplied to the electron discharge source 61 and the gasflow at the gas jetting port 65 can be respectively independentlycontrolled by a device (omitted from illustration).

Then, a method of manufacturing the cantilever-like displacement deviceaccording to this example will now be described.

First, the lower electrode 9-1 was formed on the substrate 1 as shown inFIG. 9 (a). As the substrate 1, a (100) Si single crystal was used. Thelower electrode was formed by a Pt film manufactured by ordinary highfrequency sputtering to be evaporated to have a thickness of 0.1 μm, andthen ordinary photolithography was used to perform the lift off processso that the unnecessary portion was removed.

Then, the piezoelectric thin film 8 composed of two layers wascontinuously formed as shown in FIG. 9 (b). The film forming process wasperformed by using the ion beam evaporating device shown in FIG. 11.According to this embodiment, ZnO, which is a typical piezoelectricmaterial, was used to form the aforesaid piezoelectric thin film 8. Bothof the first layer 8-1 and the second layer 8-2 of the piezoelectricthin film 8 were formed under the same conditions except for theionizing current and the accelerating voltage.

The vacuum chamber 8 was exhausted to a pressure level of 5×10⁻⁵ Pa orlower, and Zn, which is the raw material of the thin film, was chargedinto the evaporating source 69 before it was evaporated by heat. Then,an O₂ gas was introduced through the gas jetting port 65 at a speed of12 ml/min. to be sprayed to the surface of the substrate, so that thefilm was formed. The temperature of the substrate was made to be 200° C.

First, the first layer 8-1 of the piezoelectric thin film 8 was formedto have a thickness of 0.3 μm under the above-described film formingconditions while making the ionizing current to be 50 mA and theaccelerating voltage to be 0.5 kV. Then, the second layer 8-2 wasconsecutively stacked to have a thickness of 0.3 μm under the aforesaidfilm forming conditions while making the ionizing current to be 100 mAand the accelerating voltage to be -0.5 kV in such a manner that thepolarity was reversed.

After the piezoelectric thin film 8 had been formed, the upper electrode9-2 was, as shown in FIG. 9 (c), formed in such a manner that Pt wasevaporated by a thickness of 0.1 μm by the ordinary high frequencysputtering, unnecessary portions of the piezoelectric thin film 8 andthe upper electrode 9-2 were removed by the ordinary photolithography asshown in FIG. 9 (d), the potassium hydroxide solution was used toperform the anisotropic etching process to remove the one side portionof the device, and the substrate and the protection layer in the lowerportion of the device were removed.

The cantilever-like displacement device manufactured by the methodaccording to this example was 500 μm long and 50 μm wide.

In a case where a voltage of ±3 V was applied to a portion between thelower electrode 9-1 and the upper electrode 9-2 of the thus manufacturedthin film cantilever-like displacement device, the leading portion ofthe cantilever was vertically displaced by ±5 μm when viewed in FIGS. 9(a) to 9 (e).

The warp of the cantilever portion in a state where no voltage wasapplied after the cantilever had been formed was 0.5 μm or less whenmeasured at the leading portion. The change in the warp of thecantilever portion taken place when the atmospheric temperature waschanged with no voltage applied was very small such that 0.1 μm or lessin a temperature range from 0° C. to 100° C. Furthermore, neither crackswere observed nor film separation was found in the film for use to formthe device. Furthermore, no defect due to the aforesaid problems wasobserved in the operation.

Then, as shown in FIG. 9 (e), the cantilever type probe which uses thethus manufactured cantilever-type displacement device was formed in sucha manner that the micro-tip 11 for inputting and/or outputtinginformation was formed at the free end of the device and the electrodein the circuit portion and that of the cantilever portion were broughtinto contact by the electrode layer 10. The micro-tip 11 was formed byadhering metal pieces such as Pt, Rh and W.

Then, an example in which the STM information processing apparatus wasmanufactured by using the cantilever-type probe according to thisexample will now be described. FIG. 11 is a block diagram whichillustrates the apparatus. After the micro-tip 11 had been allowed tocome closer to a sample 27 by a cantilever-type probe 28 manufactured bythe method according to this example (in the vertical direction whenviewed in FIG. 11), the directions X and Y in the plane of the sample 27were scanned by an X-Y stage 22. Then, voltage was applied to themicro-tip 11 and the sample 27 by a bias voltage applying circuit 26.The tunnel current to be observed at this time is read by a tunnelcurrent amplifying circuit 24 so as to observe the image. The control ofthe distance between the sample 27 and the micro-tip 11 and that of thedrive of the X-Y stage 22 are performed by a drive control circuit 29.The sequence control of the aforesaid circuits is performed by a CPU 25.As the mechanism for scanning with the X-Y stage 22, a control mechanism(omitted from illustration) such as a cylindrical piezoelectricactuator, a parallel spring, an operational micrometer, a voice coil andan inch-worm is used.

The aforesaid apparatus was used to observe the surface of the sample27, which was an HOPG (graphite) plate. The bias voltage applyingcircuit 26 was used to apply a DC voltage of 200 mV to a portion betweenthe micro-tip 11 and the sample 27. In this state, the micro-tip 11 wasused to scan the sample 27 and a signal detected by using the tunnelcurrent detection circuit 24 was used to observe the surface. When thescan area of 0.05 μm×0.05 μm was observed, an excellent image of theatom was obtained.

As described above, the operation to be performed on the basis of theprinciple of the STM was confirmed and information recording and/orreproducing and surface observation operations were confirmed.

EXAMPLE 5

This example is so arranged that a similar device to that according toExample 4 was used, the material of the piezoelectric thin film 8 wasZnO, the deposition was performed by the sputtering method, thepolarization direction between the first layer 8-1 and the second layer8-2 was reversed by changing the material of the target of thesputtering operation between Zn and ZnO.

Similarly to Example 4, the lower electrode 9-1 is first formed on theprotection layer 7 as shown in FIG. 9 (a). As the substrate 1, (100) Sisingle crystal was used. The lower electrode was formed by using the Ptfilm by the ordinary sputtering process to be evaporated to have athickness of 0.1 μm. Then, the unnecessary portions were removed by thelift off process by ordinary photolithography.

Then, the piezoelectric thin film 8 composed of two layers wascontinuously formed as shown in FIG. 9 (b). The film forming conditionswere made commonly to either target that the temperature of thesubstrate was 200° C., the sputter gas was a mixture of Ar and O₂ at amixture ratio of 1:1, the gas pressure was 0.5 Pa and the plasma powerfor performing the sputtering was 200 W.

First, the first layer 8-1 of the piezoelectric thin film 8 was formedunder the aforesaid film forming conditions by using an Zn target whilemaking the thickness of the film to be 0.3 μm. Then, the second layer8-2 was consecutively formed by stacking to have a thickness of 0.3 μmunder the aforesaid film forming conditions by using an ZnO target.

After the piezoelectric thin film 8 had been formed, the upper electrode9-2 was, as shown in FIG. 9 (c), formed in such a manner that Pt wasevaporated by a thickness of 0.1 μm by the ordinary high frequencysputtering, unnecessary portions of the piezoelectric thin film 8 andthe upper electrode 9-2 were removed by the lift off process of ordinaryphotolithography as shown in FIG. 9 (d), the potassium hydroxidesolution was used to perform the anisotropic etching process to removethe one side portion of the device, and the substrate and the protectionlayer in the lower portion of the device were removed.

The cantilever-like displacement device manufactured by the methodaccording to this example was 500 μm long and 50 μm wide.

In a case where a voltage of ±3 V was applied to a portion between thelower electrode 9-1 and the upper electrode 9-2 of the thus manufacturedthin film cantilever-like displacement device, the leading portion ofthe cantilever was vertically displaced by ±5 μm when viewed in FIGS. 9(a) to 9 (e).

Then, similarly to Example 4, the cantilever type probe was formed insuch a manner that the micro-tip 11 for inputting and/or outputtinginformation was formed at the free end of the thus manufacturedcantilever type displacement device and the electrode in the circuitportion and that of the cantilever portion were brought into contact bythe electrode layer 10. By using it, an STM and an informationprocessing apparatus which used the STM were manufactured, resulting inan excellent operation similar to Example 4 to be performed.

EXAMPLE 6

This example is arranged so that the polarization direction of the firstlayer 8-1 and that of the second layer 8-2 of the piezoelectric thinfilm 8 are reversed in the device similar to Example 4 by forming adoped portion between the layers.

Similarly to Example 4, as shown in FIG. 9 (a), the Pt lower electrode9-1 was formed on the Si (100) substrate 1 while intervening theprotection layer 7. Then, as shown in FIG. 9 (b), ZnO was used as thematerial and the ion beam evaporating method was employed similarly toExample 4, so that the first layer 8-1 of the piezoelectric thin film 8was formed. The film forming conditions and the thickness were made tobe the same.

Then, Al was evaporated to a thickness of 0.002 mm in the same vacuumwhile maintaining the substrate temperature at 200° C. The aforesaid Alis diffused in the upper surface of the first layer 8-1 of the ZnOpiezoelectric thin film 8 and changes the crystalline characteristics ofonly the surface portion. Then, the second layer 8-2 of thepiezoelectric thin film 8 was formed under the same film formingconditions to have the same film thickness.

After the piezoelectric thin film 8 had been formed, the upper electrode9-2 was, as shown in FIG. 9 (c), formed in such a manner that Pt wasevaporated by a thickness of 0.1 μm by the ordinary high frequencysputtering, unnecessary portions of the piezoelectric thin film 8 andthe upper electrode 9-2 were removed by the ordinary photolithography asshown in FIG. 9 (d), the potassium hydroxide solution was used toperform the anisotropic etching process to remove the one side portionof the device, and the substrate in the lower portion of the device wasremoved.

The cantilever-like displacement device manufactured by the methodaccording to this example was 500 μm long and 50 μm wide.

In a case where a voltage of ±3 V was applied to a portion between thelower electrode 9-1 and the upper electrode 9-2 of the thus manufacturedthin film cantilever-like displacement device, the leading portion ofthe cantilever was vertically displaced by ±5 μm when viewed in FIGS. 9(a) to 9 (e). As described above, a cantilever-type displacement devicehaving the same performance as that according to Example 4 could bemanufactured.

Then, similarly to Example 4, the cantilever type probe was formed insuch a manner that the probe 11 for inputting/outputting information wasformed at the free end of the thus manufactured cantilever typedisplacement device and the electrode in the circuit portion and that ofthe cantilever portion were brought into contact by the electrode layer10. By using it, an STM and an information processing apparatus whichused the STM were manufactured, resulting in an excellent operationsimilar to Example 1 to be performed.

EXAMPLE 7

This example is so arranged that the polarization direction of the firstlayer 8-1 and that of the second layer 8-2 of the piezoelectric thinfilm 8 were reversed in the device similar to Example 4 by forming aportion into which halogen such as F is doped between the layers.

Similarly to Example 4, as shown in FIG. 9 (a), the Pt lower electrode9-1 was formed on the Si (100) substrate 1 while intervening theprotection layer 7. Then, as shown in FIG. 9 (b), ZnO was used as thematerial and the ion beam evaporating method was employed similarly toExample 4, so that the first layer 8-1 of the piezoelectric thin film 8was formed. The film forming conditions were made to be the same and thethickness was similarly made to be 0.1 μm. At this time, when theuppermost portion of 0.05 μm of the first layer 8-1 was formed, that is,F was mixed by 50% with the oxygen gas to be sprayed to only the finalportion of the deposition of this layer so as to dope F so that thestate of the thin film was changed. Then, the second layer 8-2 of thepiezoelectric thin film 8 was formed under the same film formingconditions as the process for forming the first layer 8-1 to have thesame thickness as that of the first layer 8-1.

After the piezoelectric thin film 8 has been formed, the upper electrode9-2 was, as shown in FIG. 9 (c), formed in such a manner that Pt wasevaporated by a thickness of 0.1 μm by ordinary high frequencysputtering, unnecessary portions of the piezoelectric thin film 8 andthe upper electrode 9-2 were removed by the ordinary photolithography asshown in FIG. 9 (d), the potassium hydroxide solution was used toperform the anisotropic etching process to remove the one side portionof the device, and the substrate in the lower portion of the device wasremoved.

The cantilever-like displacement device manufactured by the methodaccording to this example was 500 μm long and 50 μm wide.

In a case where a voltage of ±3 V was applied to a portion between thelower electrode 9-1 and the upper electrode 9-2 of the thus manufacturedthin film cantilever-like displacement device, the leading portion ofthe cantilever was vertically displaced by ±5 μm when viewed in FIGS. 9(a) to 9 (e). As described above, a cantilever-type displacement devicehaving the same performance as that according to Example 4 could bemanufactured.

Then, similarly to Example 4, the cantilever type probe was formed insuch a manner that the micro-tip 11 for inputting/outputting informationwas formed at the free end of the thus manufactured cantilever typedisplacement device and the electrode in the circuit portion and that ofthe cantilever portion were brought into contact by the electrode layer10. By using it, an STM and an information processing apparatus whichused the STM were manufactured, resulting in an excellent operationsimilar to Example 1 to be performed.

EXAMPLE 8

This example is so arranged that the material of the piezoelectric thinfilm 8 was made to be PbTiO₃, which is a ferroelectric material, and thepolarization direction of the first layer 8-1 and that of the secondlayer 8-2 of the piezoelectric thin film 8 were reversed in the devicesimilar to Example 4 by reforming the surface of the first layer byirradiating it with Ar plasma after the first layer had been depositedso as to change the state of crystal of the second layer to be depositedon it.

Similarly to Example 4, as shown in FIG. 9 (a), the Pt lower electrode9-1 was formed on the Si (100) substrate 1 while intervening theprotection layer 7. Then, as shown in FIG. 9 (b), PbTiO₃ was used as thematerial and high frequency sputtering was used, so that the first layer8-1 of the piezoelectric thin film 8 was formed. The film formingconditions were made that the target was PbTiO₃ sintered material, thesubstrate temperature was 600° C., the sputtering gas was a mixture ofAr and O₂ at a ratio of 1:1, the gas pressure was 0.5 Pa and the plasmapower at the sputtering process was 200 W.

After the first layer 8-1 had been formed, the surface of this layer wascontinuously irradiated with Ar plasma in the same vacuum chamber. Thegas pressure at this time was 0.5 Pa, the high frequency power was 200W, and the plasma irradiation was performed for about 2 minutes. Afterthe surface of the first layer 8-1 had been reformed, the second layer8-2 of the piezoelectric thin film 8 was formed under the same filmforming conditions as those for forming the first layer 8-1 to have thesame thickness as that of the first layer 8-1.

After the piezoelectric thin film 8 had been formed, the upper electrode9-2 was, as shown in FIG. 9 (c), formed in such a manner that Pt wasevaporated by a thickness of 0.1 μm by the ordinary high frequencysputtering, unnecessary portions of the piezoelectric thin film 8 andthe upper electrode 9-2 were removed by ordinary photolithography asshown in FIG. 9 (d), the potassium hydroxide solution was used toperform the anisotropic etching process to remove one side portion ofthe device, and the substrate in the lower portion of the device wasremoved.

The cantilever-like displacement device manufactured by the methodaccording to this example was 500 μm long and 50 μm wide.

In a case where a voltage of ±3 V was applied to a portion between thelower electrode 9-1 and the upper electrode 9-2 of the thus manufacturedthin film cantilever-like displacement device, the leading portion ofthe cantilever was vertically displaced by ±8 μm when viewed in FIGS. 9(a) to 9 (e).

Then, similarly to Example 4, the cantilever type probe was formed insuch a manner that the micro-tip 11 for inputting and/or outputtinginformation was formed at the free end of the thus manufacturedcantilever type displacement device and the electrode in the circuitportion and that of the cantilever portion were brought into contact bythe electrode layer 10. By using it, an STM and an informationprocessing apparatus which used the STM were manufactured, resulting inan excellent operation similar to Example 4 to be performed.

EXAMPLE 9

This example is so arranged that the material of the piezoelectric thinfilm 8 was made to be PbTiO₃, which is a ferroelectric material, and thepolarization direction of the first layer 8-1 and that of the secondlayer 8-2 of the piezoelectric thin film 8 were reversed in the devicesimilar to Example 4 by reforming the surface of the first layer byirradiating it with O₂ plasma after the first layer had been depositedso as to change the state of crystal of the second layer to be depositedon it.

Similarly to Example 4, as shown in FIG. 9 (a), the Pt lower electrode9-1 was formed on the Si (100) substrate 1 while intervening theprotection layer 7. Then, as shown in FIG. 9 (b), PbTiO₃ was used as thematerial and the ion beam evaporation was used, so that the first layer8-1 of the piezoelectric thin film 8 was formed. The film formingoperation was performed by using the ion beam evaporating device shownin FIG. 10 which comprised the evaporation source 69 having the crucibleand the heating device, the electron discharge source 61, theaccelerating electrode 62 and two ion gun portions 63 each of which iscomposed of an accelerating power source. The vacuum chamber 8 wasexhausted to a pressure level of 5×10⁻⁵ Pa or lower and PbO and Ti,which are the raw materials of the thin film, were charged into the twoevaporation sources 69 before they were evaporated by heat. Furthermore,O₂ gas was introduced through the gas jetting port 65 at a rate of 12ml/min., and the film was formed while spraying it to the surface of thesubstrate. The PbO and Ti ionizing currents were made to be 100 mA, andthe accelerating voltage was 0.5 kV. The substrate temperature was 500 °C. and the thickness of the film was made to be the same as thataccording to Example 4.

After the first layer 8- 1 had been formed, the surface of this layerwas continuously irradiated with a plasma of a mixture gas of O₂ and Arin the same vacuum chamber. The ratio O₂ :Ar was 2:1, the gas pressureat this time was 0.5 Pa, the high frequency power was 200 W, and theplasma irradiation was performed for about 2 minutes. After the surfaceof the first layer 8-1 had been reformed, the second layer 8-2 of thepiezoelectric thin film 8 was formed under the same film formingconditions as those for forming the first layer 8-1 to have the samethickness as that of the first layer 8-1.

After the piezoelectric thin film 8 had been formed, the upper electrode9-2 was, as shown in FIG. 9 (c), formed in such a manner that Pt wasevaporated by a thickness of 0.1 μm by the ordinary high frequencysputtering, unnecessary portions of the piezoelectric thin film 8 andthe upper electrode 9-2 were removed by the ordinary photolithography asshown in FIG. 9 (d), the potassium hydroxide solution was used toperform the anisotropic etching process to remove one side portion ofthe device, and the substrate in the lower portion of the device isremoved.

The cantilever-like displacement device manufactured by the methodaccording to this example was 500 μm long and 50 μm wide.

In a case where a voltage of ±3 V was applied to a portion between thelower electrode 9-1 and the upper electrode 9-2 of the thus manufacturedthin film cantilever-like displacement device, the leading portion ofthe cantilever was vertically displaced by ±8 μm when viewed in FIG. 9.

Then, similarly to Example 4, the cantilever type probe was formed insuch a manner that the micro-tip 11 for inputting and/or outputtinginformation was formed at the free end of the thus manufacturedcantilever type displacement device and the electrode in the circuitportion and that of the cantilever portion were brought into contact bythe electrode layer 10. By using it, an STM and an informationprocessing apparatus which used the STM were manufactured, resulting inan excellent operation similar to Example 1 to be performed.

EXAMPLE 10

This example is so arranged that the material of the piezoelectric thinfilm 8 was made to be PbTiO₃, which is a ferroelectric material, and thepolarization direction of the first layer 8-1 and that of the secondlayer 8-2 were reversed in the device similar to Example 4 by making thetemperature of the substrate different at the time of depositing thethin film.

Similarly to Example 4, as shown in FIG. 9 (a), the Pt lower electrode9-1 was formed on the Si (100) substrate 1 while intervening theprotection layer 7. Then, as shown in FIG. 9 (b), PbTiO₃ was used as thematerial and the sol and gel method was used, so that the first layer8-1 of the piezoelectric thin film 8 was formed by the following method:

First, the alkoxide compound of each of Pb and Ti, which are the rawmaterials of the thin film, were mixed and the density was adjustedwhile dissolving in alcohol, so that raw material liquid was prepared.Then, the aforesaid raw material liquid was caused to drop on thesubstrate 1, on which the lower electrode 9-1 had been formed and whichhad been heated to 400° C. Then, the substrate was rotated at a speed of3000 revolutions/minute to be subjected to spin coating. Since the thinfilm was deposited to a thickness of 0.1 μm by each of the aforesaidprocesses, it was repeated three times. Hence, the first layer wasformed to have a thickness of 0.3 μm. Then, the temperature of thesubstrate was lowered to 300° C. and spin coating was performedsimilarly to the process for forming the first layer 8-1, so that thesecond layer 8-2 was formed. However, since the thickness of the thinfilm deposited by one time of the spinning coating process became 0.075μm, the spin coating process was repeated four times so as to make thethickness of the second layer 8-2 to be 0.3 μm. After the aforesaidprocess had been completed, an electric furnace was used to perform theheat treatment in an oxygen atmosphere at 600 ° C. for one hour, so thatthe piezoelectric thin film 8 was formed.

After the piezoelectric thin film 8 had been formed, the upper electrode9-2 was, as shown in FIG. 9 (c), formed in such a manner that Pt wasevaporated by a thickness of 0.1 μm by the ordinary high frequencysputtering, unnecessary portions of the piezoelectric thin film 8 andthe upper electrode 9-2 were removed by the ordinary photolithography asshown in FIG. 9 (d), the potassium hydroxide solution was used toperform the anisotropic etching process to remove one side portion ofthe device, and the substrate in the lower portion of the device wasremoved.

The cantilever-like displacement device manufactured by the methodaccording to this example was 500 μm long and 50 μm wide.

In a case where a voltage of ±3 V was applied to a portion between thelower electrode 9-1 and the upper electrode 9-2 of the thus manufacturedthin film cantilever-like displacement device, the leading portion ofthe cantilever was vertically displaced by ±8 μm when viewed in FIG. 9.

Then, similarly to Example 4, the cantilever type probe was formed insuch a manner that the micro-tip 11 for inputting and/or outputtinginformation was formed at the free end of the thus manufacturedcantilever type displacement device and the electrode in the circuitportion and that of the cantilever portion were brought into contact bythe electrode layer 10. By using it, an STM and an informationprocessing apparatus which used the STM were manufactured, resulting inan excellent operation similar to Example 1 to be performed.

In addition to the aforesaid effects, the cantilever-like displacementdevice according to the present invention can be arranged so that theintermediate electrode can be omitted from the conventional cantilevercomprising the piezoelectric bimorph. Therefore, the stress controlbetween the layers of the piezoelectric thin film can be easilyperformed, causing the problem of the film separation at the interfaceto be overcome. Furthermore, the generation of cracks in thepiezoelectric film can be prevented. Therefore, a thin film cantilevertype displacement device, which can be formed into a multi-cantileverstructure, which can be integrated, and which exhibits satisfactorydurability against repeated displacement, and a cantilever-type probecan be stably provided by a simple manufacturing process.

Although the invention has been described in its preferred form with acertain degree of particularly, it is understood that the presentdisclosure of the preferred form has been changed in the details ofconstruction and the combination and arrangement of parts may beresorted to without departing from the spirit and the scope of theinvention as hereinafter claimed.

What is claimed is:
 1. A probe drive mechanism, comprising:a cantileverportion having a piezoelectric layer disposed between electrode layers,a micro-tip for detecting a tunnel current and an electrode forreceiving said tunnel current; a processing circuit portion, positionedadjacent to said cantilever portion, which drives said cantileverportion and detects and amplifies said tunnel current; a substrate forsupporting said cantilever portion and said processing portion; and aprotection layer covering said circuit portion and a portion of saidsubstrate, wherein said cantilever portion is formed on said protectionlayer adjacent to said processing circuit portion.
 2. A probe drivemechanism according to claim 1, wherein the thickness of said protectionlayer is in a range from 3000Å to 12000Å.
 3. A probe drive mechanismaccording to claim 1, wherein the thickness of said protection layer isin a range from 5000Å to 12000Å.
 4. A probe drive mechanism according toclaim 1, wherein said substrate is made of silicon.
 5. A probe drivemechanism according to claim 1, wherein material of said electrode layerin said circuit portion is aluminum or an aluminum-silicon alloy.
 6. Aprobe drive mechanism according to claim 1, wherein said processingcircuit portion includes a first insulating layer of silicon oxide.
 7. Aprobe drive mechanism according to claim 1, wherein said processingcircuit portion includes a second insulating layer of silicon oxide. 8.A probe drive mechanism according to claim 1, wherein said cantileverincludes an electrode made of noble metal.
 9. A probe drive mechanismaccording to claim 1, wherein the piezoelectric material in saidcantilever portion is selected from a group consisting of AlN, ZnO, Ta₂O₃, PbTiO₃, Bi₄ Ti₃ O₁₂, BaTiO₃ and LiNbO₃.
 10. A probe drive mechanismaccording to claim 1, wherein the material of said protection layer isSiON, Si₃ N₄ or SiO₂.
 11. A probe drive mechanism, comprising:acantilever portion having a piezoelectric layer disposed betweenelectrode layers, a micro-tip for detecting a tunnel current and anelectrode for receiving said tunnel current; a processing circuitportion positioned adjacent to said cantilever portion which drives saidcantilever portion and detects and amplifies said tunnel current; asubstrate for supporting said cantilever portion and said circuitportion; and a protection layer covering said circuit portion and aportion of said substrate, wherein said cantilever portion is formed onsaid protection layer adjacent to said circuit portion, and saidpiezoelectric layer of said cantilever portion is composed of aplurality of stacked layers having polarization axes in differentpolarization directions.
 12. A probe drive mechanism according to claim11, wherein the thickness of said protection layer is in a range from3000Å to 12000Å.
 13. A probe drive mechanism according to claim 11,wherein the thickness of said protection layer is in a range from 5000Åto 12000Å.
 14. A probe drive mechanism according to claim 11, whereinsaid substrate is made of silicon.
 15. A probe drive mechanism accordingto claim 11, wherein said circuit portion includes an electrode layermade of aluminum or an aluminum-silicon alloy.
 16. A probe drivemechanism according to claim 11, wherein said processing circuit portionincludes a first insulating layer of silicon oxide.
 17. A probe drivemechanism according to claim 11, wherein said processing circuit portionincludes a second insulating layer of silicon oxide.
 18. A probe drivemechanism according to claim 11, wherein material of said electrodelayers in said cantilever portion is noble metal.
 19. A probe drivemechanism according to claim 11, wherein said piezoelectric material insaid cantilever portion is selected from a group consisting of AlN, ZnO,Ta₂ O₃, PbTiO₃, Bi₄ Ti₃ O₁₂, BaTiO₃ and LiNbO₃.
 20. A probe drivemechanism according to claim 11, wherein an interface of saidpiezoelectric layer has an intermediate layer disposed between upper andlower layers, and said intermediate layer has a polarization directiondifferent from the polarization direction of said upper and lowerpiezoelectric layers.
 21. A probe drive mechanism according to claim 11,wherein said piezoelectric layer includes an upper, a lower and anintermediate layer disposed between said upper and lower layers, and thepolarization direction of polarization axes of said piezoelectric layercontinuously changes between said upper and lower layer and saidintermediate layer.
 22. A probe drive mechanism according to claim 11,wherein said piezoelectric layer has a plurality of stacked layers, eachof which is deposited so that spontaneous polarization directionsthereof become different at the time of depositing said piezoelectriclayer.
 23. A probe drive mechanism according to claim 11, wherein thethickness of said piezoelectric layer is in a range from 500Å to 10 μm.24. A probe drive mechanism according to claim 11, wherein the thicknessof said electrode layers is in a range from 1/3 to 1/10 of the thicknessof said piezoelectric layer.
 25. A probe drive mechanism according toclaim 11, wherein said piezoelectric layer has a plurality of layersmade of the same material.
 26. A probe drive mechanism according toclaim 11, wherein the material of said protection layer is SiON, Si₃ N₄or SiO₂.
 27. A multiple probe drive mechanism, comprising:a plurality ofprobe drive mechanisms, each comprising: a cantilever portion having apiezoelectric layer disposed between electrode layers, a micro-tip fordetecting a tunnel current and an electrode for receiving the tunnelcurrent; a processing circuit portion, positioned adjacent to saidcantilever portion, which drives said cantilever portion and detects andamplifies the tunnel current; a substrate for supporting said cantileverportion and said processing portion; and a protection layer coveringsaid circuit portion and a portion of said substrate, wherein saidcantilever portion is formed on said protection layer adjacent to saidprocessing circuit portion, wherein said probe drive mechanisms areformed on the same substrate.
 28. A probe drive mechanism according toclaim 27, wherein said piezoelectric layer in said cantilever portion iscomposed of a plurality of stacked layers having polarization axes indifferent polarization directions.
 29. A probe drive mechanism accordingto claim 28, wherein the material of said protection layer is SiON, Si₃N₄ or SiO₂.
 30. A scanning tunnel microscope, comprising:a cantileverportion having a piezoelectric layer disposed between electrode layers,a micro-tip for detecting a tunnel current and an electrode forreceiving the tunnel current; a processing circuit portion, positionedadjacent to said cantilever portion, which drives said cantileverportion and detects and amplifies the tunnel current; a substrate forsupporting said cantilever portion and said processing portion; aprotection layer covering said circuit portion and a portion of saidsubstrate, wherein said cantilever portion is formed on said protectionlayer adjacent to said processing circuit portion; means for relativelymoving said micro-tip with respect to a sample having a surface to beobserved; means for applying voltage between said micro-tip and thesample; and means for detecting an electric current which passes betweensaid micro-tip and the sample.
 31. A scanning tunnel microscopeaccording to claim 30, wherein said piezoelectric layer in saidcantilever portion is composed of a plurality of stacked layers havingpolarization axes in different polarization directions.
 32. A scanningtunnel microscope according to claim 30, wherein the material of saidprotection layer is SiON, Si₃ N₄ or SiO₂.
 33. A method of using a probedrive mechanism in a scanning tunnel microscope, the probe drivemechanism having a cantilever portion with a piezoelectric layerdisposed between electrode layers, a micro-tip for detecting a tunnelcurrent and an electrode for receiving said tunnel current, a processingcircuit portion, positioned adjacent to the cantilever portion, whichdrives the cantilever portion and detects and amplifies the tunnelcurrent, a substrate for supporting the cantilever portion and theprocessing portion, a protection layer covering the circuit portion anda portion of said substrate, wherein the cantilever portion is formed onthe protection layer adjacent to the processing circuit portion, saidmethod comprising the steps of:relatively moving the micro-tip withrespect to a sample having a surface to be observed; applying a voltagebetween the micro-tip and the sample, and detecting an electric currentwhich passes between the micro-tip and the sample.